Dormant Tree Cycle

Seasonal Cycles: Why Do Trees Go Dormant?

In school we all learn how many wild animals, like chipmunks and bears, hibernate in the winter to survive the cold temperatures and low food supply. Unfortunately, trees can’t burrow down in a den to escape the harsh months, but they do go through a similar process called dormancy to stay alive.

What is Dormancy?

Dormancy, like hibernation, is all about energy conservation. When trees slow their growth and energy consumption to survive winter this process is called dormancy.

A tree’s metabolism slows during dormancy, so all nutrition it has stored is used slowly and for essential functions only. Similar to hibernation, where animals store food as fat, trees also aren’t making new food for energy throughout the winter and rely upon food previously stored in their system. As a result, tree’s growth is stalled.

It’s common knowledge that trees lose their leaves in the fall and this is a stage of dormancy. Leaves require energy to maintain and since trees don’t make food in the winter, they drop their leaves to conserve energy. This process helps keep the tree alive during the winter months. The bare branches may give the illusion that our trees are dying but the underground and interior parts of the tree are very much alive.

How Does Dormancy Work?

During warm months trees grow actively and generate “food” through the process of photosynthesis. Sunlight triggers the process in the tree’s leaves to turn carbon dioxide and water into carbohydrates that becomes energy throughout the growing season.

In fall, when temperatures begin to drop, and days shorten with less sunlight the process of photosynthesis decelerates. Water and carbohydrates travel down into the root system where they are used to sustain the tree during the dormancy period.

When temperatures begin to rise again, the tree comes out of dormancy and these nutrients make their way from the roots into the tree canopy to provide food for the tree and begin photosynthesis once again.

How Do I Care for a Dormant Tree?

Trees need to go dormant to survive winter’s conditions, cold temperatures, and lack of sunlight. Otherwise, the tree would die from a lack of water resources due to frost, or not produce enough energy to sustain itself. Caring for dormant trees will help keep them healthy and reduce problems during the growing season.

Mulching is an easy way to care for your trees. By applying a 2-4” thick layer of mulch over the area directly under the outer circumference of the tree branches, while being careful to not pile too much against the trunk, you will provide a blanket for its roots. This will act as insulation during extreme temperatures and help the roots remain active during dormancy.

Winter pruning is another way to care for your trees. While dormant, it can be an excellent time to trim back some trees. Diseases, such as oak wilt and Dutch elm, are spread by beetles attracted to fresh cuts. Pruning during winter months while insects are at bay, helps avoid this problem and spread of disease.

Is My Tree Dead or Dormant?

Without leaves, it can be difficult to know whether a tree is dead or dormant. During the months when there are no leaves on a tree you can check by bending a twig. A dead tree is brittle and will snap, however a dormant tree should still be flexible. Another way is more obvious, watch for a tree to start sprouting buds in spring, if it doesn’t, it is probably dead.

Dormancy is a natural process to help trees survive our cold winters, however if you’re not sure whether your tree is dead or dormant, give us a call. Professional arborists are experienced in differentiating between the two, even when it may not be obvious to the untrained eye.

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